Property management company seeks property management solution

We are in the real estate industry - property management - and are looking for property management software. We manage over 400 units (residential and commercial) that are privately owned and held by limited liability companies.

The solution should meet the following requirements:

• All standards, rent adjustments - everything that property management software should do
• Modern, capable of further development
• Client accounting - we would like to use this software for financial accounting and sales tax as well, in order to save on existing financial accounting software
• Data transfer or migration from the old system must be possible
• Windows-compatible

Three to five software workstations are planned.